This multi-institutional, category D study has been completed. The study drug is a selective competitive inhibitor of neutral endopeptidase and angiotensin-converting enzyme. Inhibition of neutral endopeptidase prevents enzymatic inactivation of atrial naturetic peptide and brain naturetic peptide, potentiating diuretic and vasodilatory effects. Since angiotensin-converting enzyme inhibition increases circulating renin, neutral endopeptidase may antagonize this effect by causing an increase in atrial naturetic peptide, which inhibits renin secretion. Data collected on this study was forwarded to the industrial sponsor. Results of the study will be made available after data from all participating centers has been analyzed.